Background: Bacteria and yeasts can produce biofilm in vitro and in vivo. The biofilm can protect against host defences and antifungals. Invasive pulmonary aspergillosis is an increasing cause of morbidity and mortality in immunocompromised patients. The aim of this study was to investigate the ability of A. fumigatus to form a biofilm-like matrix in vitro on different substrates. Methods: A. fumigatus ATCC #9197 produced biofilm under different concentrations of glucose, FBS and pH in RPMI. Temperature, production time and different flow conditions were varied on polystyrene (PS) and bronchial epithelia cells (BEC). Dry weight measurement and antifungal susceptibility testing was performed. Scanning electron microscopy (SEM) and confocal scanning laser microscopy (CSLM) images were analyzed. Results: The thickest biofilm was produced on PS with RPMI (+10% glucose, +10% FBS, pH=6.5) at 35Â°C for 72h slightly rocking. Dry weight at 24h production time was increased 23 fold in comparison to the planktonic control, both on PS and BEC. Planktonic A. fumigatus was susceptible to itraconazole (0.125Âµg/ml), voriconazole (0.063Âµg/ml) and amphotericin B (1Âµg/ml). Aspergillus in biofilm was resistant against all drugs (>32Âµg/ml). The SEM pictures displayed a network of hyphal structures and matrix at 12h. Characteristic flow channels were observed at 72h. CSLM images displayed conidia and hyphal structures embedded in matrix formations. A-Alexafluor dyed polysaccharides of the cell wall and of the extracellular matrix in the biofilm. Conclusions: A. fumigatus is able to form a biofilm-like structure in vitro on PS and BEC. A biofilm-like matrix produced by A. fumigatus was evidenced by dry weight measurement, SEM, CSLM and antifungal drug resistance in comparison to planktonic cells. Potential clinical implications of A. fumigatus biofilm formation in vivo require further attention and investigations.
Full conference title:
46th Interscience Conference on Antimicrobial Agents and Chemotherapy
- ICAAC 46th